506th Fighter Group - VLR History

VII Fighter Command operations from Iwo Jima, April-August 1945

Major John A. Russ

AIR POWER HISTORY, Volume 48, number 3, Fall 2001

On April 7, 1945, 119 P-51 Mustangs of the Seventh Fighter Command lifted off from Iwo Jima (Map)(Satellite View) on the first Very Long Range (VLR) mission by land-based fighter aircraft against the Japanese mainland. Off the coast of Honshu they rendezvoused with more than 100 B-29 Superfortress bombers for an attack on the Nakajima aircraft plant in Tokyo. The B-29s had been taking heavy losses to Japanese fighters on these Empire strikes, but the 110 to 125 who came up to greet them this day were in for a surprise.

VII Fighter command pilots described the Japanese, who attacked singly during the bomb run and immediately after, as easy targets for the Mustangs that broke off in pairs to engage them. (1) One P-51 pilot, Maj. James B. Tapp (later to become the first ace from his Mustang group) recorded three kills on the mission; another pilot, Capt. Robert W Moore, got two within 45 seconds. Lieutenant E. L. Bright described his banner day (one kill and two probable's) this way: "I saw about 50 fighters. The ones I saw were just sitting ducks. You just drove up behind them and pulled the trigger." (2) Combined, the American fighters and bombers accounted for 71 Japanese aircraft destroyed, along with 30 probably destroyed of the 44 that were damaged. Sergeant Burdell Hanson, who viewed the action from the gunner's position in a B-29, noted: "The Mustangs were knocking Japs down all over the sky. For a while there during the fight there were Japs parachuting down all around us. I'll never forget it." (3)

The history of the Seventh Air Force, One Damned Island After Another, claims that this mission "was one of the few combat air actions of the Pacific where it could be said honestly that the men who did the fighting were motivated by revenge." (4) Three years and four months previously, the 14th Pursuit Wing of the Hawaiian Air Force, predecessors of the VII Fighter Command, had been decimated by the surprise Japanese attack on Pearl Harbor. Fighter pilots who were able to get airborne on December 7, 1941, managed to shoot down twelve of the attackers, (5) but it would be a long time before they were again in a position to directly attack the enemy. In the interim, units of the VII Fighter Command fought the war mainly from the sidelines.

Within ten days of the attack on Pearl Harbor, the 14th Pursuit Wing became part of the newly created 7th Interceptor Command, which consolidated all Hawaiian Islands defense units. In May 1942, the unit was re designated the VII Fighter Command, constituting the fighter arm of Seventh Air Force, and its defensive responsibilities expanded to include Midway and the Canton and Christmas Islands. (6) During the assault on the Marshall's by Seventh Air Force bombers that began in late 1943, VII Fighter Command pioneered the use of long range fighter escort in the Pacific theater. Medium bombers attacking the island chain were being harassed by Japanese fighters who would begin their attacks after the bombing run and break off at the point they estimated to be the maximum range of Seventh Air Force fighters. The Seventh eventually fitted some of its P-40s with belly tanks, and on January 26, 1944, sent them out to wait above the clouds for the pursuing Japanese. They shot down ten enemy fighters in three minutes, effectively ending interception of the bombers over the Marshalls. (7)

By March 1944, VII Fighter Command was back on Oahu for regrouping, reinforcement, aircraft transition, and general reorganization in preparation for the Marianas campaign. (8) Its strength was increased from four squadrons to three complete fighter groups of three squadrons each. (9) It was during the Marianas operations that the command began their transition from a static defensive unit in the rear to the spearhead of the attacks on Japan. VII Fighter Command participated in the seizure and consolidation of that island group and, more importantly, gained valuable experience in long-range operations, escorting B-24 Liberators on strikes to Iwo Jima (MAP) and Truk from its base in Saipan (MAP) . (10)

From the beginning, the nature of war in the Central Pacific had been different from any other. The operational objectives had not been to gain land masses or capture cities. Rather, each island objective seized became an airfield from which the next jump forward could be supported. For the B-29 Superfortresses of the XXI Bomber Command, the Marianas represented the beginning of the war's final phase. From bases on Guam, Tinian (MAP) , and Saipan (MAP) , the heavy bombers were finally within range of Japan proper. Beginning on Thanksgiving Day 1944, the Superfortress massive bomb loads would be directed at Japan's industrial centers.

There were two critical shortcomings of the Marianas bases that would have to be solved before the full destructive power of the bombers could be realized. First was the lack of a suitable divert field for battle damaged or fuel-deficient aircraft if they could not make the 1,500-mile over-water return trip. Second, and more critical, was the lack of fighter escort. Occasionally the bombers would run into a cloud of as many as 300 Japanese fighters over their target area and have to fend off as many as 600 individual attacks during the 45 minutes, or longer, they were over Japan. While the enemy's air arm was in decline, a new threat had emerged that threatened for awhile to halt to B-29 operations-the Kamikaze. Kamikaze pilots seemed unstoppable as they flung their aircraft in suicide missions against targets in the air or on the surface. Even if hit repeatedly by the bomber's gunners, they were often able to maintain enough control of their aircraft to crash into a vulnerable Superfortress. (12) A small, volcanic island a little more than five miles long and barely two miles across was the answer to both of these problems.

Situated about halfway between Saipan and Honshu, Iwo Jima was the site of two crude Japanese airfields and a third in the early stages of construction. Air planners hoped to eventually base as many as 150 B-29s on Iwo Jima, after neutralizing the surrounding islands and building up the runways and facilities to bomber specifications. (13) This effort was not completed by the end of the war, but after the U.S. Marines took it, Iwo would serve as an emergency divert field for the bombers and allow basing VII Fighter Command's P-51's within range of Japan. Central Pacific forces under Admiral Chester Nimitz landed on February 20, but it was not until March 16, after weeks of fierce fighting that resulted in more than 24,000 American casualties and 20,000 Japanese dead, that the island was declared secure. (14) VII Fighter Command was tasked to move to the island during the assault phase of the amphibious operation, support the engaged ground forces, provide air defense, and be ready as soon as possible to begin escorting XXI Bomber Command to the Empire. (15)

Besides the immediate problem of moving 6,200 men, over 400 fighter aircraft, and air defense warning and fighter direction equipment over 4,500 miles from Oahu to Iwo, the command would have to battle the factors that had been plaguing the forward-deployed air units since the beginning of the war. The long intra theater distances and even longer lines of communication and supply from the United States meant that equipment spent a lot of time "in the pipeline." Since the Pacific theater was secondary in the grand scheme of the war, the amount of supplies entering that pipeline was always conditioned by the needs of the European theater, meaning that Army Air Forces allocations were kept near the absolute minimum required for safe operations. Further, the primitive islands of the Pacific were not only lacking in production facilities and skilled labor but also in diversion or recreation opportunities for those stationed there. Morale was an early casualty of the primitive living conditions and far-- too-infrequent rotations. (16)

Fortunately, the VII Fighter Command was still too fresh to these forward operations to have lost its morale and, besides, such mundane concerns paled by comparison to the tremendous challenges they would have to overcome in mounting effective VLR operations. Foremost among these were the physical, mental, and technical stresses of routinely operating fighter aircraft over unprecedented distances over water. Navigation and pilot rescue were two of the greatest technical challenges initially faced, and ingeniously tackled, by Fighter Command. Weather, more specifically its unpredictability and unforgiving nature, was to be the biggest threat to operations. Communications, intelligence, and maintenance round out the list of major headaches that would continue to menace operations. While each of these areas, besides the distance problem, are common to all air operations, it is useful to show how the particular nature of this operation exacerbated them, and the initial solutions worked out by the command.

Earlier in the war, VII Fighter Command P-40s and P-47s had some long range experience in both the Marshalls and Marianas campaigns, but the 15th and 21st Fighter Groups, the first of the units deployed to Iwo Jima, were equipped with P-51D Mustangs. Although used extensively in the ETO, the command had only started receiving them in December and there was no precedent for flying these aircraft to their maximum range over water. (17) In preparation for the upcoming VLR operations, the groups flew a training mission on March 30, escorting B-29s from Iwo Jima to Saipan and back. That route corresponded closely to the 1,500 mile round trip to Japan and provided the fighter pilots valuable experience in escort formations, using the B-29s for homing and navigation information, and physically coping with the stress and anxiety of a seven and a half hour over water flight in the cramped cockpit of an aircraft with notoriously poor ditching characteristics. (18)

Since it was likely that battle damage or increased fuel consumption in combat would preclude a number of P-51s from completing the return trip to Iwo Jima, an extensive network of Air Sea Rescue (ASR) stations was set up along the route. The equipment supporting ASR duties included B-29 "Super Dumbo" aircraft to locate and coordinate pickup of downed pilots, B-17s with deployable motor boats, P-51 "Josephines" with specially-fitted deployable life rafts, destroyers, other surface vessels, and submarines. (19) The command eventually established seven standard routes to Japan and designated for each five ASR stations along the return route of the fighters. (20) The first station, and by far the busiest, was located at the "rally point", a location close to the enemy coast where the fighters rendezvoused with their navigation B-29s at the completion of the mission. Here the distressed airman would find a surfaced submarine covered by a Super Dumbo and a four-ship fighter escort. One hundred miles further on was a second station manned by a submarine and Super Dumbo, then a third sub at the midway point, and a destroyer at each of the two remaining stations. (21) Finally, for those pilots who almost made it, but ran out of gas at the last minute, Fighter Command had amphibious vehicles waiting on the beaches of Iwo. (22) The system was constantly improved as operational experience was gained and, by June, a very adequate system was in place.

Navigating to the nearest ASR facility, or to Japan and Iwo Jima for that matter, was another technical problem that would require some ingenuity on the part of VII Fighter Command planners. Because precision navigation equipment was not practical in a single-seat fighter, B-29s with special crews were assigned as "navigator" aircraft and the command's fighters were fitted with the AN/ARA-8 homing radio. After takeoff, the fighters would rejoin as groups over Iwo Jima, and then proceed about 40 miles north, to Kita Jima, where they would link up with a navigator B-29 waiting to lead them to the drop off point near the coast of Japan. (23) After the mission over Japan, the homing radio-nicknamed "Uncle Dog" because the correct course to the parent station was found by flying halfway between the "U" and "D" tones (24) would allow the fighters to find the navigator B-29, now holding at the rally point and transmitting a continuous tone on one of the P-51s preset radio frequencies. Each ASR station was capable of broadcasting the homing tone if needed, and it was continuously broadcast from a station on Iwo which was usable by the fighters once they arrived within about 150 miles.

The greatest barrier to effective VLR operations was one that no amount of technical ingenuity could fully overcome: the unpredictable frontal weather of the Western Pacific. Throughout the campaign, weather accounted for more than half of the aborted missions and the official command history called it "undoubtedly the most important single deterring and restricting factor." (25) Hazardous weather fronts formed along an east-west line between Iwo Jima and Japan where high pressure systems moving south and southeast from the Asian mainland clashed with warmer air over the Pacific. These fronts were frequently quite broad and contained embedded thunderstorms, turbulence, and icing conditions-all extremely hazardous to the single-seat P-51s. During the initial months of the campaign, these fronts usually formed just south of Iwo Jima, causing low ceilings and poor visibility that could make landings hazardous, if not impossible. In late spring and early summer, as high pressure systems moving off Siberia and across Japan became weaker and less frequent, the fronts generally formed across the fighters' route of flight to Japan. As the fronts migrated further north throughout the summer, bad weather frequently obscured targets and forced the fighters to attack at lower altitudes. (26)

Fighter pilots departing on VLR missions received the most current forecast thirty minutes before takeoff but, with the limited forecasting tools available, this amounted to little more than an educated guess. (27) Attempting to get a more accurate picture of what the fighters would really be facing, the command tried various permutations of weather reconnaissance flights sent out ahead of the fighter groups, eventually obtaining B-24 aircraft specifically for this role. One would take off the night before to reach a position off the coast of Japan around dawn. While flying its return trip to Iwo above any weather, another would launch and fly the route below the clouds. Additionally, one of the navigator B-29s would be launched about 100 miles ahead of the fighters to provide continuous reports on the current conditions ahead. (28) To deal with bad weather on recovery, VII Fighter Command established in early April the only operational Ground Controlled Approach capability in the combat theater. (29) Notwithstanding all these efforts, at times Mother Nature could still find a way to imperil unsuspecting P-51s.

Communications, like navigation, was a challenge because the fighters spent most of their flying time over open ocean. The single VHF radio on the P-51 had a range of approximately 150 miles, or line-of-sight to the horizon. An incident on May 17th illustrates how the risks exacerbated each other. While the 21st Fighter Group was out sweeping the skies over Atsugi, dense fog moved in over Iwo Jima. Repeated attempts to contact the fighters and divert them to Okinawa failed. By the time contact was made, the P-51s had jettisoned their drop tanks and were committed to a landing at Iwo. Were it not for a timely break in the fog the entire group might have been lost. (30) Afterward, the command kept a series of B-24s spread out along the route of flight to act as radio relays whenever the fighters were out of radio range with the base.

Since VII Fighter Command was soon flying almost daily missions over the Empire, they had reasonably good intelligence about Japan's capabilities and the continuing decline of its air force. What they lacked was up-to-date target intelligence, particularly photographs. By late June, the enemy was using camouflage and decoys and moving its aircraft around so much that recent photos were essential if the P-51s were to find aircraft to strafe. Pilots were sometimes unable to find targets or, worse yet, spent too much time flying low, in range of anti-aircraft guns, trying to find them. (31) It was not until August 8, a week before the war's end, that adequate photo reconnaissance assets arrived on Iwo Jima. (32)

Harsh conditions on Iwo would make aircraft maintenance a challenge throughout the campaign. Extreme humidity and constantly blowing volcanic dust wreaked havoc on fighter engines and flight controls. Water, moisture, and dirt frequently clogged carburetor impact tubes and damaged radiators, while corrosion attacked fuselages, flight control surfaces and cables, and electrical equipment. Spark plugs proved particularly troublesome, even though they were constantly checked and changed after every other mission. To achieve the range required on VLR missions, the engine was operated for very long periods at minimum power settings, leading to lead fouling of the plugs. (33) All of these factors increased the potential for engine failure. Runways were nearly as hard to maintain as the aircraft. Underground sulfur steam caused soft spots to develop and tropical storms eroded the soil. Coupled with the fact that most takeoffs and landings were accompanied by great clouds of dust or by water rushing across the runway, it is no wonder that accidents were common. In fact, nearly as many aircraft were lost to accidents as were lost in combat-103 versus 114. (34)

VII Fighter command had to contend with these adverse conditions, and many more, as they began operations from Iwo Jima on March 10, six days before the island was declared secure. By the end of the month, two fighter groups, the 15th and 21st, along with the 548th and 549th Night Fighter Squadrons were operating on Iwo and preparing for the upcoming VLR missions. (35) Even before they got to attack the enemy in the skies over Japan, however, they found themselves in a battle right in their own front yard. On the night of March 27, hundreds of Japanese who had survived the invasion emerged from caves on the northern end of the island and attacked the bivouac near Air-field No. 1, where newly-arrived VII Fighter Command crews and support personnel were sleeping. In the morning, after a bitter and confusing fight that lasted most of the night, 333 Japanese bodies lay sprawled over the northeast corner of the island. Forty-four Americans had been killed, along with 88 wounded. (36)

Following the initial VLR escort mission on April 7, another was flown on April 12, again to the Nakajima factory. During this mission the fighters scored 15 air-to-air kills, 6 aircraft probably destroyed, and 3 damaged. Friendly losses were 4 P-51s. (37) On the third and last escort mission in April, poor weather in the target area prevented the fighters from finding the bombers, who had passed up the primary target for their radar backup attack. For the month of April, 14 B-29s were shot down by enemy aircraft on unescorted missions, but no Japanese pilot could claim a bomber kill on escorted missions. (38) A study by Army Air Forces headquarters, Pacific Ocean Area, concluded, "It is clearly apparent that in the first month the provision of escort for very heavy bombers has proven markedly successful." (39) The report predicted that results would continue to improve as the fighter pilots became more experienced at escort, coordination improved, facilities at Iwo Jima developed, and additional fighter groups joined Fighter Command.

However, even at this early stage of the campaign, the escort mission was already fading in importance. Japanese resistance to daylight raids declined as the enemy began hoarding aircraft in anticipation of an Allied invasion. Also, B-29s started putting more emphasis on night incendiary attacks as cloud cover increasingly obscured targets during the day. (40) This allowed Fighter Command to concentrate on a much more efficient means of attacking enemy air power-fighter sweeps and strikes against airfields. The first independent mission, flown on April 16, was plagued by weather problems and no estimate of damage could be made. (41) Attacks on April 19 and 22, however, proved the efficacy of independent fighter missions. Of the 56 Japanese fighters encountered in the air, 32 were destroyed and three more damaged. The P-51s achieved such complete surprise with their low level strafing runs that the initial wave over the Kanoya airfield received a green light from the tower (clearance to land) on their approach. In addition to the air-to-air victories, 30 aircraft were destroyed and 70 damaged by ground attack. (42)

Strikes and sweeps proved more effective because much less coordination was required and, not tied to the bomber stream, the fighters were free to search out and destroy Japanese aircraft wherever they could be found. (43) The command would generally designate a combat group of three 16-aircraft squadrons to carry out airfield attacks. One squadron remained in a high cover position to protect the strikers from the enemy air threat. Meanwhile, a second squadron would plan its attack to ensure that all major anti-aircraft artillery sites were under fire as the third squadron came through on its strafing runs. (44) Destruction of Japanese aircraft on the ground proved to be the best method of protecting the B-29s.

The P-51s left the target area at 1410, and climbed towards the RP [Rally Point] which was reached at 1425. 4 planes and pilots were lost during the mission. 2 pilots are known to have reached the RP, but they did not return to base. They are considered missing. 1 pilot was last seen at low altitude in the vicinity of Oise, but he did not return to base, and he is considered missing. On return to base one pilot, because of a coolant leak, was forced to parachute midway between two Air Sea Rescue positions. His parachute was observed to be pulling him face down in the water, and it is believed he drowned. Remaining fighters landed at base from 1700-1730. One fighter, with hydraulic system shot away, crashed upon landing, the pilot suffering minor injuries. One fighter was holed in the left wingtip by flak. (45)

During the initial month of VLR operations, Japanese aircraft and air defenses were not the only distractions faced by VII Fighter Command as they struggled to establish "normal" operations at Iwo Jima. On April 24, a B-29 went out of control during an emergency landing, destroying four P-51s and damaging five. The next day the command saw its headquarters destroyed when a flare landed in a stack of demolition tubes and the resultant fire spread to the ammunition dump. There also remained a security threat from the numerous Japanese who had "gone to ground" during the seizure of the island. On the 28th, five enemy soldiers were discovered in the vicinity of the central airfield. (46) Nonetheless, the unit made a good account of itself on its initial missions. Its 867 VLR sorties accounted for 192 enemy aircraft destroyed or damaged at a cost of 21 P-51s. (47)

In May, the threat of Japanese air attack on Iwo Jima decreased to the point that VLR escort replaced air defense as the primary Fighter Command mission. (48) Combat power continued to increase on Iwo Jima as a third airfield became operational and a third fighter group, the 506th, began flying VLR operations. Enemy resistance to strikes varied from nil to very aggressive. During the first escort for a B-29 incendiary raid, on May 29 against Yokohama, it was intense. Around 150 Zekes came up to meet the massive strike force and, while 58 were destroyed, probably destroyed, or damaged, they managed to shoot down five B-29s and damage 175 more. (49) For the month, the command flew 741 VLR sorties on two escort and five strike missions. The tally was 234 Japanese aircraft destroyed or damaged at a cost of 11 P-51s. (50)

Weather had its greatest impact on operations during June, canceling seven missions and rendering five of the eleven flown non-effective. (51) In fact, the most costly mission ever flown over the Pacific was caused by weather. (52) On June 1, 148 P-51s were launched on an escort mission to Osaka. En route to the rendezvous the fighters encountered a solid overcast up to 23,000 feet. Reports from the weather ship led them to believe that they would only be in the clouds for a brief period so the formation plunged into the front. Inside they found an intense, unforecasted thunderstorm with severe turbulence and icing. They were in the thick of it when the decision was finally made to turn around and, before they broke clear, 27 aircraft had either collided or lost control. Twenty-four pilots were killed. (53)

UNCLE DOG & BROTHER AGATE ON IWO JIMA

By Mark Starin K1RMC
RMC USNR (Ret.)

P-51 Equipped With Uncle Dog/Brother Agate Antennas

Introduction
The story of Uncle Dog and Brother Agate on Iwo Jima is a relatively unknown aspect of the US Army Air Force operations on the island. It involved the work of the 302nd Fighter Control Squadron and one of WW2’s most famous aircraft radios – the SCR-522 – as integral part of the system.

One of the earliest Iwo Jima stories I remember my father (My Starin) telling me was how he made it back alone from Japan using something he called “Brother Agate”. He described it as a VHF (Very High Frequency) homing beacon which allowed him to navigate safely back to the island. The system was patterned after the low frequency A – N systems then commonly used in the United States and adapted for VHF operation. This was the navigation system operated by the 302nd FCS on Mount Suribachi.

Typical WW2 P-51 Avionics
Let’s begin with the typical avionics package carried in most P-51’s. I say most because installations can and did vary depending upon the requirements of the theater where the Mustangs were flown.

Here is a diagram from the P-51 service manual depicting the typical avionics package for the P-51A through P-51C aircraft (note that the Uncle Dog equipment is not included):

The equipment includes the SCR-695 which was a multiband airborne transponder which allowed the plane to be identified on friendly radars. Also included is the SCR-522 four channel VHF radio set which was used for air-to-air and air-to-ground communications (plus navigation in the 506th P-51D’s). Not shown is the BC-453/R-23 medium frequency (MF) direction finding (DF) receiver which was installed on many pre-1945 P-51’s.

Early P-51 DF Receiver System
The early P-51’s (A through C model plus early D’s) used the standard BC-453/R-23 Command Receiver which could receive continuous wave (CW) or modulated continuous wave (MCW) in the 190 – 550 KHz band. The R-23 was a compact six tube receiver and is shown below:

The antenna was typically either a wire antenna which ran from the cockpit back to the vertical stabilizer (BC-453) or a hand rotatable loop (R-23) which could be mounted in several locations on the fuselage (see 82nd Fighter Group P-51H photo). Although beacons in the MF band had a reliable frequency range of up to 50 miles, there were several problems with this system:

Noise – static crashes made listening for the beacons very difficult, especially in the summer months

Bidirectional signals – it was possible to receive MF beacon signals on a primary bearing and a reciprocal bearing (180 degrees opposite the primary) which could lead to the pilot missing an airfield, running out of fuel, or worse

An example of how easy it was to follow a reciprocal instead of the primary bearing is shown in the case of the B-24D “Lady Be Good” in 1943. The navigator, not being sure of his location and thinking he was still over the Mediterranean Sea instead of land, followed the reciprocal bearing past the airfield at Soluch, Libya into the Libyan Desert where the plane crashed after the crew bailed out. The plane and the remains of the crew were not located until 1959.

Enter Uncle Dog
It became apparent early in the B-29 bomber offensive against Japan that P-51 escort fighters flying from Iwo Jima would be needed to counter the Japanese Navy Raiden (Jack) fighters among others. In order for the Mustangs to fly the long distance from Iwo to the Japanese home islands and return safely, some kind of electronic navigation system would be needed to: a. find the B-29’s they were escorting; and, b. find their way back. A VHF beacon system would eliminate the problems associated with the MF beacons thus providing greater reliability and accuracy.

Two kinds of beacons were established. The first was used aboard B-29’s equipped with Uncle Dog transmitters specifically tasked with serving as navigation aircraft for the fighter escorts. This signal, when received on a fighter’s SCR-522 VHF communication set (equipped with an AN/ARA-8 homing adapter and MD-34 modulator keying unit) allowed the fighters to meet the bombers at a specific predetermined location in order to ensure maximum fuel efficiency.

The beacon system aboard the fighter picked up the B-29’s signal and converted it into two audio channels consisting of the International Morse letters "U" or "D" with a steady tone separating them. Consistent with the wartime phonetic alphabet, this homing procedure was referred to as "Uncle Dog". Following the steady tone towards maximum signal strength allowed the Mustang to find its target as shown in the following diagram:

This system was not restricted to B-29 escort operations. The 302nd FCS on Iwo used it also. This unit operated the ground-based version of the SCR-522 (SCR-575) known as “Brother Agate”. In order to ensure maximum coverage forreturning fighters, the 302nd operated SCR-575 radios that transmitted "Uncle Dog" homing signals from Mt. Suribachi. These signals could be received from a few hundred miles depending on altitude, allowing the Mustangs (and many crippled B-29 bombers) to make it home despite the Siberian cold fronts that periodically plagued the island with poor visibility.

Uncle Dog Pilot Training
Uncle Dog was so new in 1945 when the 506th FG arrived on Iwo Jima that most of its pilots were totally unfamiliar with the system. As a result, it fell to the ingenious and resourceful radio mechanics (like the late M/Sgt. Charles Barr) of the group to develop an Uncle Dog simulator which would familiarize the pilots on its operating characteristics.

Here is a photo of an Uncle Dog simulator using salvaged P-51 parts, including a drop tank as a “fuselage”. Note the 458th FS colors on the “tail” of the drop tank and the Uncle Dog antennas on the aft part of the “fuselage”.

The radio mechanics installed the Uncle Dog equipment inside the “cockpit” of the drop tank and rotated the whole assembly using a salvaged Japanese motor. Here is a photo of the Uncle Dog electronics:

This is a photo of M/Sgt. Charles Barr demonstrating the system:

Postwar Brother Agate/Uncle Dog
Improved versions of Brother Agate and Uncle Dog served on past 1945 well into the early 1960’s on many different aircraft. A classic example of postwar use is this photo of an 82nd FG P-51H (an improved version of the P-51D) at Grenier AFB in Manchester, NH (circa 1948):

Note the R-23 MF DF loop on the underside of the fuselage forward of the air scoop. Stateside P-51’s probably used the MF DF loop for flight navigation away from military bases because VHF beacons were not part of the civilian airways system at that time. Uncle Dog was in use when the 82nd deployed to Alaska during the 1948 Berlin Airlift.

Conclusion
Brother Agate and Uncle Dog saved the lives of many USAAF pilots on long range missions in the Pacific Theater in 1945. It also led to the postwar development of many other advanced navigations systems which are taken for granted today like VOR, TACAN, and others. None of this would have been possible without the dedication of the engineers who designed the equipment, the technicians who made it work, and the heroic efforts of the pilots themselves.
Sources

On the positive side in June, pilots were gaining experience with VLR operations and developing more fuel efficient techniques for operating their fighters. The extra gas allowed more time over target and an extension of attacks to the airfields north and east of Tokyo where the bulk of the remaining Japanese air strength was concentrated. (54) A June 23 raid on these targets was the most destructive day of the campaign for the VII Fighter Command with 91 enemy aircraft destroyed or damaged. For the month only 632 of 1381 sorties were effective, but the P-51s could still claim 238 destroyed or damaged Japanese aircraft at a cost of only 29 of their own. (55) Of course, this ratio would have been even better had it not been for the weather-related disaster on the first.

Throughout the summer, Japanese air power continued to decline. Pilots were finding more dummy aircraft on the airfields, greater attempts at dispersion and camouflage, and a significant decrease in both the number and the aggressiveness of enemy aircraft opposing the attacks. (56). What few aircraft the Japanese still possessed were hidden in revetments or under trees as much as two miles from the airfield and these aircraft, when located and strafed, often had been drained of gasoline and would not burn. It was becoming obvious that the Japanese were hoarding their aircraft for the coming invasion. (57) Letters from the VII's commander, Brig. Gen. Ernest Moore, to his commanders in early July lamented the lack of opposition and requested greater leeway in target selection. (58) In one, he stated, "Our game of hide and seek with the Jap air force still continues, and the seeking becomes increasingly difficult...I hope they will at least give us a little competition, because it is not very encouraging to fly that far in hopes of combat, and not get it. (59) As a result, fighters began striking targets of opportunity on a large scale in July. (60)

While the threat was decreasing, VII Fighter Command's combat capability continued to increase. The 414th Fighter Group arrived on July 7 with three squadrons of P-47Ns. Henceforth, the command could plan for daily two-group strikes or occasional massive four-group attacks on the Empire. (61) During the period July 4 to July 10, P-51s flew VLR strikes every day. With the weather finally improving, a total of 17 VLR missions, all strike, were flown in July. (62) Japanese opposition occasionally flared and on July 8, seven aircraft were lost. The last serious opposition occurred on July 16, which was also the last mission where the command achieved significant results. After that there was practically no aerial opposition and most of the enemy's aircraft were removed from the airfields at Nagoya, Osaka, Kobe, and Tokyo and widely dispersed throughout the country. (63)

During the last month of the war, a concerted effort was made to provide maximum coverage of the remaining Japanese aircraft reserve. Between July 16 and August 14, the tempo of operations increased with the command flying sixteen VLR strike missions. (64) Forty-one airfields in Osaka, Nagoya, Kobe, and Tokyo were struck, putting an additional 168 enemy aircraft out of commission. The Japanese took desperate measures to defend what few aircraft they possessed. Pilots attacking airfields encountered little air resistance but they did find barrage balloons and kites obstructing their route, land mines detonating in their path, and all caliber weapons available firing at them. At Tokorozawa airfield, the Japanese stretched a 50-foot high cable across the field. (65) Consequently, pilots attacked many secondary targets, scoring hits on gun positions, radar towers, locomotives, freight trains, ammunition dumps, shipping, docks, and warehouses. (66) The final VLR mission was a massive four-group effort flown on August 14, the last day of the war.

Had the war continued beyond the middle of August, VII Fighter Command would have continued to bring increasing combat power to bear on the enemy. One squadron of P-47Ns had just begun operations at the beginning of August and another was on the way. The P-47 was the aircraft that General Moore had always wanted for the VLR mission. Its greater fuel and payload capacity allowed it to carry rockets, 500-pound bombs, and parachute-retarded fragmentation bombs, long with its eight .50 caliber machine guns. The P-5 Is had also been fitted with rocket launchers that would allow them to attack pinpoint targets that remained after the B-29's area bombing. (67) The end of the war in Europe, in May, had finally eased the manning and ammunition shortages that had hindered operations earlier. In short, Fighter Command had overcome the tremendous difficulties of VLR operations and was ready to support the planned invasion with ever-increasing offensive capability.

With so many cumulative influences eroding Japan's will and ability to wage war in August 1945, it is difficult to determine the decisiveness of VII Fighter Command's efforts. There is no doubt, however, that what they did accomplish was remarkable given the conditions and limitations under which they operated. Overall, 41 of 51 VLR missions were effective and the 4,172 effective sorties destroyed or damaged 1,062 aircraft, 254 surface vessels, 134 locomotives, 355 railroad cars, 246 buildings and hangars, 16 radio/radar stations, 10 oil tanks, and 13 trucks. (68) Perhaps the biggest contribution of Iwo Jima and VII Fighter Command was recovering and servicing B-29s that could not make it back to the Marianas. In five months of operations, about 2400 made emergency landings at Iwo. (69) The cost of the campaign to Fighter Command was 157 aircraft and 91 pilots. (70) Had it not been for the effective ASR network, an additional 57 pilots would almost certainly been lost at sea. (71) .

After spending most of the war defending rear area air bases and training replacement pilots for other commands, during the spring and summer of 1945 VII Fighter Command was in a position to strike directly at the Japanese Empire and offensively contribute to its defeat. It overcame tremendous challenges to establish an effective VLR capability for the Iwo Jima campaign. As the Seventh Air Force history points out, "Each long range mission successfully carried out would have had the stature of a legend if it had been a single mission rather than part of a continuing series of missions." (72) These efforts hastened the defeat of Japanese air power and would have facilitated the planned invasion of mainland Japan, had the war continued. That VII Fighter Command not only carried out these missions effectively, but by the end had almost made them routine, is one of the great success stories of the war in the Pacific.

NOTES

1. Clive Howard and Joe Whitley, One Damned Island after Another (Chapel Hill: University of North Carolina Press, 1946), p. 347.

Maj. John A. Russ, USAF, is Chief of Strategy, Twelfth Air Force at Davis-Monthan AFB, Arizona. A graduate of the Air Force Academy, Maj. Russ also earned an MBA from Texas Tech University, a Master of Military Operational Art and Science from the Air University, and graduated from the School of Advanced Warfighting. A pilot, he has logged more than 2,500 hours in T-37, F-111, and A-10 aircraft, including Operations Northern Watch and Southern Watch.